Lord Ganesha is one of the most famous and loved gods of Hinduism.  
Lord Ganesha was born as a normal child to Lord Siva and Goddess Parvathi, but came later to have a change of form and fate.  Lord Siva was an ascetic and for all of his marriage, he liked to roam in the forest. Right after the conception of their son, Ganesha, he decided to start a new journey, and told his faithful wife, Parvathi, to wait, he would return soon. He did not return for about 15 years, about the time Ganesha would be a teenager.  From a young age, Ganesha knew he had a father, somewhere wandering in the forest, but never did he see him. Due to this, Ganesha would protect his mother by standing guard the house each day, especially at the time for her bath. So, one day, she was bathing, and Siva returned from the forest. Remember that Siva knows he has a son, but has been gone for such a long time, he would not know how he looks. Similarly, Ganesha also would not know how his father would look. So, when Lord Shiva returned, Ganesha unknowingly told his father to go away, as mother is bathing and I cannot let anyone, especially strange men into the house. Siva could not bear some stranger telling him not to enter his own house, so after some time, he chopped the head off of Ganesha and went inside to his wife, Parvathi, who was bathing. Parvathi shouted, "How can you come into the house, is not Ganesha there to protect me?" Siva said he did not know anything about Ganesha, but had come in by beheading the man guarding the door! Parvathi wailed and shouted, "How can you kill our only son!??" 
At that time, Siva knew what damage he had done. And Parvathi asked him to bring Ganesha back to Life. Siva said, "How can I do that? His head is severed and can not be reconnected!" Parvathi agreed that Siva should take the head off of the first living being in the area and attach it to the body of her son, so that he could live. Siva had saw one elephant, and beheaded that elephant and attached that head to his son. That is one of many stories of how Ganesha has the head of an elephant. These are following questions some have asked me regarding Lord Ganesha. 1. Why do I like Lord Ganesha? At one time, I was only curious about Hinduism, and considered myself an atheist. But something happened to me. I visited a Hindu temple. At the time it did not strike me much more than a new and exciting experience. But sometime later, visions of Ganesha came to me in daytime, waking hours and in my sleep. I had many dreams of Ganesha in different forms. I never had visions or dreams of God before this one of Ganesha. In one such dream, Jesus also came. It was quite a revelation for me. I pray to many Gods, of Hinduism and Christianity, but somehow Ganesha is always there for me, to help me overcome my obstacles.